Finishing a plasterboard partition with badly filled joints is what makes the steps between boards show under raking light even after painting. Joint compound is cheap; the time to redo the work is not.
How much joint compound is needed
Joint compound is applied in 2–3 coats with tape between boards so the join is invisible after painting, with an approximate consumption of 0.35 kg per m² of installed board.
Worked example: for 25 m² of installed board: 25 × 0.35 = 8.75 kg, rounded up to 1 bag of 25 kg. This is the same calculation the PresupuestoYa calculator applies automatically for the Drywaller trade.
The first coat closes the joint with the tape embedded; the following ones spread and feather the width so the step between boards isn't noticeable under raking light. Sand lightly between coats.
Bonding compound: much higher consumption than joint compound
If the job is direct dry-lining (bonding the board straight to the wall with no framing, so-called "dot-and-dab plasterboard"), bonding compound consumes considerably more: 4.5 kg per m². It is applied in dabs spread over the board, not by roller, and only works well on reasonably flat, dry walls — if the wall is very uneven, it is more reliable to build a metal frame even if it takes longer.
Joint tape: paper or mesh
- Paper: needs a first layer of fresh compound to bed into; folds well in internal corners.
- Self-adhesive fibreglass mesh: stuck on directly dry and then covered with compound, saving a step in the process.
A 10% margin for overlaps is added to the length of joints.
Frequently asked questions
How much joint compound do I need for 40 m² of board? 40 × 0.35 = 14 kg, rounded up to 1 bag of 25 kg.
Why does bonding compound use so much more than joint compound? Because it covers the whole contact surface between board and wall in dabs, not just the narrow line of a joint between two boards.
Which tape is quicker to fit, paper or mesh? Self-adhesive mesh, because it is stuck on directly dry without needing a prior layer of fresh compound to bed into.
Conclusion
Calculating the real compound consumption according to the type of job (normal joints or direct dry-lining) avoids running short halfway through the finishing. Applying several thin coats instead of one thick one, with the right tape, is what makes the joint invisible under raking light once painted.
Want to calculate this quote automatically?
PresupuestoYa calculates materials, quantities and total cost in minutes, for this and 19 other trades.
Create a free quote →